add dart-sdk option to dartdeps

pkg/analysis_server/bin/dartdeps.dart

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import 'dart:async';
 import 'dart:io';
 
 import 'package:args/args.dart';
 import 'package:analysis_server/src/analysis_manager.dart';
 
@@ skipping 15 matching lines @@
  * Instances of [_DartDependencyAnalyzer] launch an analysis server and use
  * that server to analyze the dependencies of an application.
  */
 class _DartDependencyAnalyzer {
   /**
    * The name of the application that is used to start the analyzer.
    */
   static const BINARY_NAME = 'dartdeps';
 
   /**
+   * The name of the option used to specify the Dart SDK.
+   */
+  static const String DART_SDK_OPTION = 'dart-sdk';
+
+  /**
    * The name of the option used to print usage information.
    */
   static const String HELP_OPTION = 'help';
 
   /**
    * The name of the option used to specify an already running server.
    */
   static const String SERVER_OPTION = 'server';
 
   /**
    * The command line arguments.
    */
   final List<String> args;
 
   /**
+   * The path to the Dart SDK used during analysis.
+   */
+  String sdkPath;
+
+  /**
    * The manager for the analysis server.
    */
   AnalysisManager manager;
 
   _DartDependencyAnalyzer(this.args);
 
   /**
    * Parse the command line arguments to determine the application to be
    * analyzed, then launch and manage an analysis server to do the work.
    */
   Future run() {
     return new Future(start).then(analyze).whenComplete(stop);
   }
 
   /**
    * Parse the command line arguments to determine the application to be
    * analyzed, then launch an analysis server.
    * Return `null` if the command line arguments are invalid.
    */
   Future<AnalysisManager> start() {
     var parser = new ArgParser();
+    parser.addOption(
+        DART_SDK_OPTION,
+        help: '[sdkPath] path to Dart SDK');
     parser.addFlag(HELP_OPTION,
         help: 'print this help message without starting analysis',
         defaultsTo: false,
         negatable: false);
     parser.addOption(
         SERVER_OPTION,
         help: '[serverUrl] use an analysis server thats already running');
 
     // Parse arguments
     ArgResults results;
     try {
       results = parser.parse(args);
     } on FormatException catch(e) {
       print(e.message);
       print('');
       printUsage(parser);
       exitCode = 1;
       return null;
     }
     if (results[HELP_OPTION]) {
       printUsage(parser);
       return null;
     }
+    sdkPath = results[DART_SDK_OPTION];
+    if (sdkPath is! String) {
+      print('Missing path to Dart SDK');
+      printUsage(parser);
+      return null;
+    }
+    Directory sdkDir = new Directory(sdkPath);
+    if (!sdkDir.existsSync()) {
+      print('Specified Dart SDK does not exist: $sdkPath');
+      printUsage(parser);
+      return null;
+    }
     if (results.rest.length == 0) {
       printUsage(parser);
       exitCode = 1;
       return null;
     }
     Directory appDir = new Directory(results.rest[0]);
     if (!appDir.existsSync()) {
       print('Specified application directory does not exist: $appDir');
       print('');
       printUsage(parser);
@@ skipping 46 matching lines @@
   /**
    * Print information about how to use the server.
    */
   void printUsage(ArgParser parser) {
     print('Usage: $BINARY_NAME [flags] <application_directory>');
     print('');
     print('Supported flags are:');
     print(parser.getUsage());
   }
 }